Talk talk talk with her!!! Tell her all that you want her to know, ask her all you want to know. Talk to her about death, and her wishes... yes, it's very hard to do...but you will feel better for doing it...and you will help her too.... No one is really "ready" for those last moments in time... there just seems like so much we forgot to take care of! Take pictures... smile in some of them. Try to find things you both cherish together...and share them some more.
Is there someone or ppl you can call for her, to visit her, to comfort her? What about a minister, or even faraway friends? Think out of the box, so to speak, if you can... we had Thanksgiving in June for my dad...but we only had 5 weeks from his diagnosis.
I wish you strength.